Trialing system for a knee prosthesis and method of use

Trialing system for a knee prosthesis and method of use

An orthopaedic surgical instrument system that includes an orthopaedic surgical instrument adapted to be positioned on a proximal end of a patient's tibia, and a tibial bearing trial assembly configured to be coupled to the orthopaedic surgical instrument. The tibial bearing trial assembly includes a plurality of tibial bearing surface trial components and at least one shim.Related Terms:ProsthesisTibiaSurgical Instrument

The Patent Description & Claims data below is from USPTO Patent Application 20130006370, Trialing system for a knee prosthesis and method of use.

This application claims priority under 35 U.S.C. §119 to U.S. Patent Application No. 61/503,300, which was filed on Jun. 30, 2011 and is incorporated herein by reference.

CROSS-REFERENCE

Cross-reference is made to co-pending U.S. Provisional Patent Application Ser. No. 61/503,311 entitled “SYSTEM AND METHOD FOR TRIALING A KNEE PROSTHESIS” by Tom Wogoman et al. (Attorney Docket No. 265280-214737, DEP6379USPSP); and co-pending U.S. Provisional Patent Application Ser. No. 61/503,303 entitled “METHOD OF USING A TRIALING SYSTEM FOR A KNEE PROSTHESIS” by Tom Wogoman et al. (Attorney Docket No. 265280-214738, DEP6380USPSP), each of which is assigned to the same assignee as the present application and each of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgical instruments and, more particularly, to surgical instruments used with a patient's tibia.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. A typical knee prosthesis includes a patella prosthetic component, a tibial tray, a femoral component, and a polymer insert or bearing positioned between the tibial tray and the femoral component. Femoral components are designed to be attached to a surgically-prepared distal end of a patient's femur. Tibial trays are designed to be attached to a surgically-prepared proximal end of a patient's tibia.

To facilitate the replacement of the natural joint with the knee prosthesis, orthopaedic surgeons use a variety of orthopaedic surgical instruments such as, for example, prosthetic trial components, cutting blocks, drill guides, milling guides, and other surgical instruments. Prosthetic trial components, such as, for example, a femoral trial component and a tibial bearing trial component, are used to size and select the components of the knee prosthesis that will replace the patient's natural joint. A procedure that utilizes the trial components to size and select the components of the knee prosthesis is often referred to as a trial reduction.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgical instrument system includes an orthopaedic surgical instrument adapted to be positioned on a surgically-prepared proximal end of a patient's tibia. The orthopaedic surgical instrument includes a central post that defines a longitudinal axis. The system also includes a tibial bearing trial assembly coupled to the orthopaedic surgical instrument. The tibial bearing trial assembly includes one of a plurality of tibial bearing surface trial components, each tibial bearing surface trial component having an articular surface, and a shim. The shim is configured to be coupled to a first tibial bearing surface trial component of the plurality of tibial bearing surface trial components in a first orientation in which the tibial bearing trial assembly is permitted to pivot about the axis. The shim is configured to be coupled to a second tibial bearing surface trial of the plurality of tibial bearing surface trial components in a second orientation in which the tibial bearing trial assembly is substantially prevented from rotating about the longitudinal axis.

In some embodiments, the shim may have an aperture defined therein. The aperture may include a central passageway sized to receive the central post, a first slot extending from the central passageway, and a second slot extending from the central passageway. In some embodiments, a lug may extend from the central post. The lug may be received in the first slot when the shim is positioned over the central post in the first orientation and received in the second slot when the shim is positioned over the central post in the second orientation.

In some embodiments, the orthopaedic surgical instrument may include a tibial base trial component adapted to be positioned on the surgically-prepared proximal end of the patient's tibia. The tibial base trial component may have an upper surface configured to contact the shim when the tibial bearing trial assembly is coupled to the orthopaedic surgical instrument. Additionally, in some embodiments, the orthopaedic surgical instrument may include a base insert adapted to be positioned in an opening defined in the tibial base trial component. The base insert may have the central post extending therefrom.

In some embodiments, the orthopaedic surgical instrument may include a keel punch adapted to be positioned in an opening defined in the tibial base trial component. The keel punch may include a main platform having the central post extending upwardly therefrom, and a pair of arms extending outwardly from the main platform. The pair of arms may be configured to be positioned in the surgically-prepared proximal end of the patient's tibia.

In some embodiments, each tibial bearing surface trial component may include a pair of pegs extending downwardly therefrom, and the shim may include a pair of attachment openings. Each attachment opening may be sized to receive one of the pair of pegs to removably couple each tibial bearing surface trial component to the shim.

According to another aspect, an orthopaedic surgical instrument system includes an orthopaedic surgical instrument having a central post defining a longitudinal axis, and a shim including an aperture configured to receive the central post. The shim is configured to be positioned on the orthopaedic surgical instrument in a first orientation in which the shim is permitted to pivot about the longitudinal axis, and a second orientation in which the shim is prevented from rotating about the longitudinal axis. In some embodiments, the aperture may include a central passageway sized to receive the central post of the orthopaedic surgical instrument, and a slot extending from the central passageway. The slot may be defined by an arcuate inner wall extending between a pair of planar inner walls. In some embodiments, the arcuate inner wall may define an arc extending approximately fifty degrees.

In some embodiments, the orthopaedic surgical instrument may include a lug extending from the central post. The lug may be configured to be received in the slot when the shim is positioned on the orthopaedic surgical instrument in the first orientation such that when the shim is pivoted in a first direction about the longitudinal axis, a first planar inner wall of the pair of planar inner walls is advanced into contact with the lug, and when the shim is pivoted in a second direction about the longitudinal axis, a second planar inner wall of the pair of planar inner walls is advanced into contact with the lug.

In some embodiments, the aperture of the shim may include a second slot extending from the central passageway, and the lug may be received in the second slot when the shim is positioned on the orthopaedic surgical instrument in the second orientation. In some embodiments, the second slot may be defined by a pair of inner walls configured to engage the lug when the lug is received in the second slot such that the shim is substantially prevented from rotating about the longitudinal axis.

In some embodiments, the system may further include a tibial bearing surface trial component including an articular surface configured to contact a pair of femoral condyles and a bottom surface having a pair of pegs extending downwardly therefrom. The shim may include a pair of attachment openings. Each attachment opening may be sized to receive one of the pair of pegs to removably couple the tibial bearing surface trial component to the shim.

Additionally, in some embodiments, the tibial bearing surface trial component may be permitted to be secured to the shim when the shim is positioned in the first orientation and prevented from being secured to the shim when the shim is positioned in the second orientation. In some embodiments, the pair of pegs may include a first peg and a second peg having a peg size different from the first peg, and the pair of attachment openings may include a first attachment opening sized to receive the first peg and a second attachment opening sized to the receive the second peg. The second attachment opening may have an opening size different from the first attachment opening and configured to match the peg size of the second peg.

According to another aspect, an orthopaedic surgical instrument includes a tibial trial shim including a plate having a predetermined thickness. The plate has an aperture defined therein that includes a central passageway, a rectangular slot extending from a first side of the central passageway, and an arcuate slot extending from a second side of the central passageway.

In some embodiments, the plate may have a pair of attachment openings defined therein. Each attachment opening may be configured to secure the tibial trial shim to a tibial bearing surface trial component. In some embodiments, a first attachment opening of the pair of attachment openings may be defined through the plate on the first side of the central passageway, a second attachment opening of the pair of attachment openings may be defined through the plate on the second side of the central passageway, and the first attachment opening may have a different size from the second attachment opening.

Additionally, in some embodiments, the first attachment opening and the second attachment opening may be circular, and the diameter of the first attachment opening may be greater than the diameter of the second attachment opening.

In some embodiments, the orthopaedic surgical instrument may further include a plurality of tibial bearing surface trial components configured to be removably coupled to the tibial trial shim. Each tibial bearing surface trial component may have an upper bearing surface configured to contact a pair of femoral condyles and a bottom surface having a pair of pegs extending therefrom. The first attachment opening of the tibial trial shim may be sized to receive a first peg of the pair of pegs and the second attachment opening of the tibial trial shim may be sized to the receive a second peg of the pair of pegs.

In some embodiments, the plate may include a first planar surface, a second planar surface, and a sidewall extending between the first planar surface and the second planar surface. A first channel may be defined in the first planar surface. The first channel may extend inwardly from the sidewall toward the aperture. A second channel may be defined in the second planar surface. The second channel may extend inwardly from the sidewall toward the aperture.

In some embodiments, the aperture may be positioned between the first channel and the second channel. In some embodiments, the aperture may include a slot extending from the central passageway through a posterior section of the sidewall. In some embodiments, the central passageway may define an axis through the plate, and the arcuate slot may be defined by an arcuate inner wall having an edge that extends approximately fifty degrees about the axis. In some embodiments, the arcuate slot may be further defined by a pair of planar inner walls and the arcuate inner wall may extend between the pair of planar inner walls.

According to another aspect, a method of trialing prosthetic components of a knee prosthesis is disclosed. The method includes positioning a tibial base trial component on a surgically-prepared proximal end of a patient's tibia, and inserting a base insert into an opening defined in the tibial base trial component. The base insert has a central post extending upwardly from an upper surface thereof. The method also includes selecting a tibial bearing surface trial component, securing a shim to the selected tibial bearing surface trial component to form a tibial bearing trial assembly, positioning the tibial bearing trial assembly over the central post of the base insert, and adjusting the patient's leg with the tibial bearing trial assembly positioned over the central post of the base insert. If a first tibial bearing surface trial component is selected, securing the shim includes securing the shim to the first tibial bearing surface trial component in a first orientation and adjusting the patient's leg includes rotating the tibial bearing trial assembly relative to the tibial base trial component. If a second tibial bearing surface trial component is selected, securing the shim includes securing the shim to the second tibial bearing surface trial component in a second orientation such that the tibial bearing trial assembly is substantially prevented from rotating relative to the tibial base trial component.

In some embodiments, the base insert may include a lug extending from the central post, and positioning the tibial bearing trial assembly over the central post of the base insert may include positioning the lug and the central post in an aperture defined in the shim. Additionally, in some embodiments, selecting the tibial bearing surface trial component may include selecting a mobile bearing surface trial component, and securing the shim may include securing the shim to the mobile bearing surface trial component in the first orientation.

In some embodiments, rotating the tibial bearing trial assembly relative to the tibial base trial component may include moving an arcuate inner wall of the shim relative to the lug. In some embodiments, inserting the base insert into the opening defined in the tibial base trial component may include inserting a spike of the base insert into the proximal end of the patient's tibia. In some embodiments, selecting the tibial bearing surface trial component may include selecting a fixed bearing surface trial component and securing the shim may include securing the shim to the fixed bearing surface trial component in the second orientation.

Additionally, in some embodiments, positioning the tibial bearing trial assembly may include positioning the lug between a pair of planar inner walls of the shim to prevent the tibial bearing trial assembly from rotating relative to the tibial base trial component.

In some embodiments, the method may further include locating an alignment etching on the tibial base trial component and marking the proximal end of the patient's tibia at the alignment etching after adjusting the patient's leg. Additionally, in some embodiments, the method may further include removing the tibial bearing trial assembly from the base insert, and detaching the shim from the tibial bearing surface trial component. The shim may have a first predetermined thickness. The method may also include selecting a second shim having a second predetermined thickness different from the first predetermined thickness, securing the second shim to the tibial bearing surface trial component to form a second tibial bearing trial assembly, positioning the second tibial bearing trial assembly over the central post of the base insert, and adjusting the patient's leg with the second tibial bearing trial assembly positioned over the central post of the base insert.

In some embodiments, detaching the shim from the tibial bearing surface trial component may include inserting a separator tool into a channel defined in an upper surface of the shim and actuating a lever to engage a bottom surface of the tibial bearing surface trial component to separate the shim from the tibial bearing surface trial component.

In some embodiments, adjusting the patient's leg may include placing the patient's knee in flexion, attaching an alignment handle to the tibial base trial component, inserting a first alignment rod into a first passageway defined in the alignment handle, and inserting a second alignment rod into a second passageway defined in the alignment handle. The second passageway may extend orthogonal to the first passageway.

In some embodiments, securing the shim to the tibial bearing surface trial component may include positioning a pair of pegs of the tibial bearing surface trial component into a pair of openings defined in the shim. In some embodiments, the method may further include selecting a prosthetic tibial bearing component corresponding to the selected tibial bearing surface trial component and the selected shim. Additionally, in some embodiments, the method may further include removing the tibial bearing trial assembly from the base insert and the tibial base trial component, removing the base insert from the opening defined in the tibial base trial component, and impacting a keel punch into the proximal end of the patient's tibia through the opening of the tibial base trial component. The keel punch may have a central post extending upwardly from an upper surface thereof. The method may also include positioning the tibial bearing trial assembly over the central post of the keel punch, and adjusting the patient's leg with the tibial bearing trial assembly positioned over the central post of the keel punch.

According to another aspect, the method of trialing prosthetic components of a knee prosthesis includes positioning an orthopaedic surgical instrument on a surgically-prepared proximal end of a patient's tibia, and selecting a tibial bearing surface trial component. The tibial bearing surface trial component is one of a mobile bearing surface trial component and a fixed bearing surface trial component. The method also includes positioning a shim and the selected tibial bearing surface trial component on the orthopaedic surgical instrument. A first surface of the shim is positioned in contact with the tibial bearing surface trial component if the tibial bearing surface trial component is the mobile bearing surface trial component. A second surface of the shim is positioned in contact with the tibial bearing surface trial component if the tibial bearing surface trial component is the fixed bearing surface trial component.

In some embodiments, the method may further include rotating the tibial bearing surface trial component and the shim relative to the orthopaedic surgical instrument if the mobile bearing surface trial component is selected. Additionally, in some embodiments, the shim may be configured to substantially prevent the tibial bearing surface trial component from rotating relative to the orthopaedic surgical instrument if the fixed bearing surface trial component is selected. In some embodiments, the method may further include selecting a prosthetic tibial bearing component corresponding to the selected tibial bearing surface trial component and the shim.

In some embodiments, the method may further include securing the shim to the selected tibial bearing surface trial component prior to positioning the shim and the tibial bearing surface trial component on the orthopaedic surgical instrument.

According to another aspect, a method of assembling a surgical instrument includes selecting a tibial bearing surface trial component, orienting a shim relative to the tibial bearing surface trial component, and securing the shim to the tibial bearing surface trial component. The shim is secured in a first orientation relative to the tibial bearing surface trial component if the tibial bearing surface trial component is a first tibial bearing surface trial component. The shim is secured in a second orientation that is opposite the first orientation if the tibial bearing surface trial component is a second tibial bearing surface trial component.

According to another aspect of the disclosure, the method includes positioning a polymer femoral trial component on a surgically-prepared distal end of a patient's femur, assembling a tibial bearing trial component, positioning the tibial bearing trial component on a tibial base trial component seated on a surgically-prepared proximal end of a patient's tibia, adjusting the patient's leg with the tibial bearing trial component engaging the polymer femoral trial component, removing the tibial bearing trial component from the tibial base trial component, inserting a keel punch into the surgically-prepared proximal end of the patient's tibia through an opening of the tibial base trial component, placing the tibial bearing trial component on the tibial base trial component and the keel punch, and readjusting the patient's leg with the tibial bearing trial component engaging the polymer femoral trial component after positioning the tibial bearing trial component on the tibial base trial component and the keel punch. In some embodiments, adjusting the patient's leg may include moving the patient's leg between extension and flexion such that a plurality of teeth of the polymer femoral trial component grip the surgically-prepared distal end of the patient's femur.

In some embodiments, the method may further include inserting a base insert into the opening of the tibial base trial component before positioning the tibial bearing trial component on the tibial base trial component. In some embodiments, assembling the tibial bearing trial component may include securing a shim to a first tibial bearing surface trial component in a first orientation, and positioning the tibial bearing trial component includes positioning a lug of the base insert in a first slot of the shim such that the tibial bearing trial component is prevented from substantially rotating relative to the tibial base trial component.

Additionally, in some embodiments, positioning the tibial bearing trial component on the tibial base trial component and the keel punch may include positioning a lug of the keel punch in the first slot of the shim such that the tibial bearing trial component is prevented from substantially rotating relative to the tibial base trial component. In some embodiments, assembling the tibial bearing trial component may include securing the shim to a second tibial bearing surface trial component in a second orientation, positioning the tibial bearing trial component may include positioning the lug of the base insert in a second slot of the shim such that the tibial bearing trial component is permitted to substantially rotate relative to the tibial base trial component, and adjusting the patient's leg may include rotating the tibial bearing trial component relative to the tibial base trial component. In some embodiments, inserting the base insert may include inserting a spike of the base insert into the patient's tibia.

In some embodiments, positioning the tibial bearing trial component on the tibial base trial component and the keel punch may include positioning a lug of the keel punch in the second slot of the shim such that the tibial bearing trial component is permitted to substantially rotate relative to the tibial base trial component, and readjusting the patient's leg may include rotating the tibial bearing trial component relative to the tibial base trial component. Additionally, in some embodiments, the method further may include placing a guide tower on the tibial base trial component, and securing the keel punch to a lower end of a handle by engaging a lever of the handle with the keel punch. Further, inserting the keel punch into the surgically-prepared proximal end of the patient's tibia may include inserting the keel punch and the lower end of the handle through an upper end of the guide tower.

In some embodiments, positioning the polymer femoral trial component may include securing an impactor head to the handle, attaching the polymer femoral trial component to the impactor head, and tapping a head end of the handle to attach the polymer femoral trial component to the surgically-prepared distal end of the patient's femur. Additionally, in some embodiments, the method may further include installing a tibial tray of the knee prosthesis in the surgically-prepared proximal end of the patient's tibia, positioning the tibial bearing trial component on the tibial tray, and readjusting the patient's leg after positioning the tibial bearing trial component on the tibial tray.

According to another aspect, a method of trialing prosthetic components of a knee prosthesis includes positioning a femoral trial component on a surgically-prepared distal end of a patient's femur, and selecting a first femoral prosthetic component if a sidewall of the femoral trial component is positioned beyond an outer edge of the surgically-prepared distal end of the patient's femur and the surgically-prepared distal end of the patient's femur is visible through a notch defined in the sidewall of the femoral trial component, and a second femoral prosthetic component if the sidewall of the femoral trial component is positioned within the outer edge of the surgically-prepared distal end of the patient's femur. The first femoral prosthetic component is more narrow than the second femoral prosthetic component. The method also includes positioning a tibial bearing trial component on a tibial base trial component seated on a surgically-prepared proximal end of a patient's tibia, and adjusting the patient's leg with the tibial bearing trial component engaging the femoral trial component.

In some embodiments, the femoral trial component may be formed from a polymeric material. In some embodiments, the method may further include inserting a keel punch into the surgically-prepared proximal end of the patient's tibia through an opening of the tibial base trial component, positioning the tibial bearing trial component on the tibial base trial component and the keel punch, and readjusting the patient's leg with the tibial bearing trial component engaging the femoral trial component after positioning the tibial bearing trial component on the tibial base trial component and the keel punch.

In some embodiments, the method may further include selecting a tibial bearing surface trial component from a plurality of tibial bearing surface trial components, orienting a shim relative to the tibial bearing surface trial component, and securing the shim to the tibial bearing surface trial component to assemble the tibial bearing trial component. The shim may be secured in a first orientation relative to the tibial bearing surface trial component if the tibial bearing surface trial component is a first tibial bearing surface trial component. The shim may be secured in a second orientation that is opposite the first orientation if the tibial bearing surface trial component is a second tibial bearing surface trial component.

In some embodiments, adjusting the patient's leg may include rotating the tibial bearing trial component relative to the tibial base trial component if the tibial bearing surface trial component is the first tibial bearing surface trial component.

According to another aspect, a method of trialing prosthetic components of a knee prosthesis includes positioning a polymer femoral trial component on a surgically-prepared distal end of a patient's femur, moving the patient's leg between extension and flexion such that a plurality of teeth of the polymer femoral trial component grip the surgically-prepared distal end of the patient's femur, and selecting a femoral prosthetic component of the knee prosthesis for implantation.

In some embodiments, the plurality of teeth of the polymer femoral trial component may extend from a posterior fixation surface defined by a plurality of ribs. The posterior fixation surface may extend generally in a superior/inferior direction. In some embodiments, selecting the femoral prosthetic component may include identifying a position of a sidewall of the polymer femoral trial component relative to an outer edge of the surgically-prepared distal end of the patient's femur. Selecting the femoral prosthetic component may also include selecting a first femoral prosthetic component if the sidewall is positioned beyond the outer edge of the surgically-prepared distal end of the patient's femur and the surgically-prepared distal end of the patient's femur is visible through a notch defined in the sidewall, and a second femoral prosthetic component if the sidewall of the polymer femoral trial component is positioned within the outer edge of the surgically-prepared distal end of the patient's femur. The first femoral prosthetic component may be more narrow than the second femoral prosthetic component.

In some embodiments, the method may further include drilling a pair of fixation holes in the surgically-prepared distal end of the patient's femur. In some embodiments, drilling the pair of fixation holes may include inserting a surgical drill into a guide hole defined in the polymer femoral trial component.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures, in which:

FIG. 1 is an exploded perspective view of an orthopaedic surgical instrument system;

FIG. 2 is a perspective view of a tibial base trial component of the orthopaedic surgical instrument system of FIG. 1;

FIG. 3 is a perspective view of a base insert component of the orthopaedic surgical instrument system of FIG. 1;

FIG. 4 is a top plan view of the base insert component of FIG. 3;

FIG. 5 is a perspective view of a femoral trial component of the orthopaedic surgical instrument system of FIG. 1;

FIG. 6 is an exploded perspective view of the tibial base trial component, the base insert component, and a number of tibial bearing trial components of the orthopaedic surgical instrument system of FIG. 1;

FIG. 7 is a top plan view of the tibial base trial component, the base insert component, and a fixed bearing trial component;

FIG. 8 is a top plan view of the tibial base trial component, the base insert component, and a mobile bearing trial component;

FIG. 9 is a perspective view of one embodiment of a trial shim of the tibial bearing trial component of FIG. 6;

FIG. 10 is a top plan view of the trial shim of FIG. 9;

FIG. 11 is a perspective view of one embodiment of a fixed bearing surface trial component of one of the tibial bearing trial components of FIG. 6;

FIG. 15 is an exploded perspective view of a keel punch used with the tibial base trial component of the orthopaedic surgical instrument system of FIG. 1;

FIG. 16 is a perspective view of a guide tower of the orthopaedic surgical instrument system of FIG. 1;

FIG. 17 is a perspective view of an alignment handle of the orthopaedic surgical instrument system of FIG. 1;

FIG. 18 is a perspective view of an impaction handle of the orthopaedic surgical instrument system of FIG. 1;

FIG. 19 is an exploded perspective view of one embodiment of a fixed bearing knee prosthesis;

FIG. 20 is an exploded perspective view of one embodiment of a mobile bearing knee prosthesis;

FIG. 21 is a simplified flow chart of one embodiment of a procedure utilizing the orthopaedic surgical instrument system of FIGS. 1-18; and

FIGS. 22-40 are views of a patient\'s femur, tibia, the knee prostheses of FIGS. 19 and 20, and the orthopaedic surgical instrument system of FIGS. 1-17 as the orthopaedic surgical instrument system is used in the procedure of FIG. 21.

DETAILED DESCRIPTION

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, etcetera, may be used throughout the specification in reference to the orthopaedic implants and surgical instruments described herein as well as in reference to the patient\'s natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in the written description and claims is intended to be consistent with their well-understood meanings unless noted otherwise.

Referring to FIGS. 1-16, an orthopaedic surgical instrument system 10 (hereinafter system 10) is shown. The system 10 is used during joint arthroplasty procedures, such as a total knee replacement procedure. It should be appreciated, however, that although the system 10 is described below in regard to the performance of a total knee replacement procedure, certain concepts associated with the system 10 may be utilized in replacement procedures of numerous other joints throughout the body.

As shown in FIG. 1, the system 10 has a number of trial components 12, including a tibial base trial 14, a number of base inserts 16, a femoral trial 18, and a number of tibial bearing trial assemblies 20. The system 10 also includes a tibial keel punch 22 (see FIG. 13) and a guide tower 24 (see FIG. 14). Additionally, the system 10 includes a number of surgical tools, such as, for example, an alignment handle 26 (see FIG. 15) and an impaction handle 28 (see FIG. 16), which are used to manipulate the trial components 12 and the other surgical instruments during the performance of an orthopaedic surgical procedure, as described in greater detail below.

The system 10 may be utilized to size and select the prosthetic components of a knee prosthesis (see FIGS. 17 and 18) that will replace the patient\'s natural joint. To do so, the femoral trial 18 is attached to a surgically-prepared distal end 600 of a patient\'s femur 602 (see FIG. 20), whereas the tibial base trial 14 is attached to a surgically-prepared proximal end 604 of a patient\'s tibia 606 (see FIG. 20). One of the tibial bearing trials 20, each of which is a multi-piece assembly, as discussed in greater detail below, is positioned on the tibial base trial 14 between the femoral trial 18 and the base trial 14. As described in greater detail below, the surgeon uses the system 10 in a trial reduction process to determine the type and configuration of each of the various types of prosthetic components that are to be implanted.

The system 10 may be also utilized to surgically prepare the proximal end 604 of a patient\'s tibia 606 for implantation of a tibial prosthetic component, such as a tibial tray, during the performance of an orthopaedic surgical procedure. The tibial base trial 14 and the guide tower 24 are positioned on the proximal end 604 of the patient\'s tibia 606, and the surgeon uses the trial 14 and the tower 24 to guide, for example, a surgical drill while reaming the proximal end 604 of the patient\'s tibia 606. Thereafter, the keel punch 22 is impacted into the proximal end 604 of the patient\'s tibia 606 before the guide tower 24 is removed. An additional trial reduction may be performed with the keel punch 22 before the surgeon installs the components of the knee prosthesis, as described in greater detail below.

Referring now to FIG. 2, the base trial 14 includes a plate 30 having an upper surface 32, a lower surface 34, and an outer sidewall 36 extending between the surfaces 32, 34. The plate 30 has a plate opening 38 defined in the upper surface 32. The plate opening 38 has a central opening 40 and a pair of elongated openings 42 extending outwardly therefrom. An inner wall 44 extends downwardly from the opening 38 to define a passageway 46 through the plate 30. The inner wall 44 includes an upper wall 48 and a lower wall 50 offset or otherwise spaced inwardly from the upper wall 48. The upper wall 48 and lower wall 50 cooperate to define a shelf surface 52 therebetween. As will be discussed in greater detail below, the configuration of the passageway 46 permits the advancement of various surgical drills, punches, and other instruments into the proximal end 604 of the patient\'s tibia 606. It should be appreciated that the tibial base trial 14 may be formed in a number of different sizes to accommodate tibias of various sizes.

The plate 30 also includes a lever-receiving notch 54 that is defined in an anterior aspect 56 thereof. The notch 54 includes a channel 58 that is defined in the upper surface 32 and extends posteriorly from the outer sidewall 36. An oblong-shaped slot 60 is defined in the posterior end 62 of the channel 58. The slot 60 extends downwardly through the lower surface 34 of the plate 30. As shown in FIG. 2, a pair of oblong-shaped apertures 64 is defined in the sidewall 36, one on each side of the notch 54. As will be discussed in greater detail below, the notch 54 and the apertures 64 are configured to receive a lever 66 and a pair of pins 68, respectively, associated with the alignment handle 26 (see FIG. 15).

A plurality of alignment etchings 70 extend along the upper surface 32 and the outer sidewall 36 of the plate 30. The surgeon may use one or more of the alignment etchings 70 to mark the proper position of the base trial 14 on the proximal end 604 of the patient\'s tibia 606 and ensure that the base trial 14 is consistently positioned at the same location thereon. The plate 30 also includes a number of fastener holes 72 that are defined in the anterior aspect 56 thereof. The fastener holes 72 are configured to receive fasteners such as fixation pins, which may be utilized to secure the base trial 14 to the proximal end 604 of the patient\'s tibia 606.

Referring now to FIG. 3, the system 10 further includes a pair of evaluation bullets or base inserts 16. The base inserts 16 are configured to be positioned separately in the plate opening 38 of the base trial 14. Each base insert 16 has a lower body 78 and an upper body 80 that cooperate to define a rim 82 around the periphery thereof. The rim 82 has a bottom surface 84 configured to engage the shelf surface 52 of the base trial 14 when the base insert 16 is seated on the base trial 14. The body 80 includes a central platform 86 sized to be received in the central opening 40 of the base trial 14. The body 80 also includes a pair of prongs 88, 90 that extend outwardly from the central platform 86. The prongs 88, 90 are sized to be received in the elongated openings 42 of the base trial 14.

The body 80 of the base trial 14 includes a post 94 extending upwardly from an upper surface 96 thereof. The post 94 extends to a top end 98, and a lip 100 extends outwardly therefrom. The lip 100 has a bottom surface 102 that extends substantially parallel to the upper surface 96, and the surfaces 96, 102 cooperate to define a lever-receiving notch 104. The lever-receiving notch 104 is configured to receive a locking flange 498 associated with the impaction handle 28, as described in greater detail below.

As shown in FIG. 4, the post 94 also has an opening 106 defined in an upper surface 108 thereof. An inner wall 110 extends downwardly from the opening 106 to define a central passageway 112 through the base insert 16. The opening 106 is configured to receive a guide pin 508 associated with the impaction handle 28 (see FIG. 16). The inner wall 110 has a keyed section 114 that permits the base insert 16 to be attached to the impaction handle 28 in only a single predetermined orientation.

The post 94 of each base insert 16 has a generally curved sidewall 116 and a flat sidewall 118 positioned under the lip 100. Each base insert 16 includes a block or lug 120 extending outwardly from the curved sidewall 116 of the post 94 toward the prong 90. As will be described in greater detail below, the lug 120 engages the tibial bearing trial 20 to prevent or permit the tibial bearing trial 20 from rotating relative to the tibial base trial 14. It should be appreciated that in other embodiments the lug 120 might extend from, for example, the other side of the post 94 toward the prong 88. It should also be appreciated that in other embodiments the base insert 16 may include additional lugs. In the illustrative embodiment, the lug 120 has a rectangular cross section, but it should be appreciated that in other embodiments the lug 120 may have, for example, a square or other geometrical cross section. As will be described in greater detail below, the post 94 and the lug 120 are positioned in the tibial bearing trial 20 when the tibial bearing trial 20 is positioned on the tibial base trial 14.

The central platform 86 of the body 80 also has a keyed section 122. The keyed section 122 and the orientation of the prongs 88, 90 relative to the platform 86 permit each base insert 16 to be inserted into the plate opening 38 of the base trial 14 in a single, predetermined orientation.

Returning to FIG. 3, the pair of base inserts 16 includes a spiked base insert 126 and a spikeless base insert 128. The spiked base insert 126 also includes a pair of mounting spikes 130 that extend downwardly from the prongs 88, 90, respectively. Each spike 130 includes an upper cylindrical section 134 and a pointed conical tip 136 configured to engage the proximal end 604 of the patient\'s tibia 606, thereby temporarily securing the base insert 126 to the proximal end 604 of the patient\'s tibia 606.

As discussed above, the system 10 also includes a femoral trial 18 that is configured to be secured to the distal end 600 of the patient\'s femur 602. One example of a femoral trial is shown and described in co-pending U.S. Patent App. Ser. No. 61/503,237, entitled “POLYMER FEMORAL TRIAL COMPONENT” by Thomas Wogoman (Attorney Docket No. 265280-210419, DEP6287USPSP), which is expressly incorporated herein by reference. The femoral trial 18 is configured to assist the surgeon in selecting a femoral prosthetic component, which will emulate the configuration of the patient\'s natural femoral condyles. As such, the femoral trial 18 includes a pair of condyle surfaces 140, 142, which may be shaped (i.e., curved) in a manner that approximates the condyles of the natural femur. The condyle surface 140 and the condyle surface 142 are spaced apart from one another, thereby defining an intercondylar notch 144 therebetween.

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